“I’m not sure who exactly thought of it, but I’m sure it was Linda!" Kroes told People. "When she heard about #KnotOnMyPlanet, she didn’t hesitate to not get involved — and no one really says ‘no’ when Linda calls!”

It's obviously a cause the legendary models all care about. "30K elephants killed a year? #KnotOnMyPlanet," Campbell captioned the picture on her Instagram. "Tie a knot. Donate. End the slaughter."